Data processing apparatus and method

A method of identifying a code word present in a watermarked material item, the watermarked material item composed of a plurality of units and the code word composed of a plurality of parts, each part including different data from the code word, the watermarked version formed by combining each of the plurality of parts of the code word with one of the plurality of units, the method comprising:

• recovering, by a hardware recovery processor, a partial code word composed of at least one of the plurality of parts of the code word from at least one of the plurality of corresponding units of the watermarked material item,
• generating for the watermarked material item a dependent correlation value by correlating the partial code word with a corresponding partial stored code word that is a part of a whole stored code word, and
• determining whether the whole code word is present in the watermarked material item based on the dependent correlation value for the partial code word exceeding a predetermined threshold,
• when the dependent correlation value does not exceed the predetermined threshold, iteratively increasing a number of parts of the partial code word used, to increase information quantity of the recovered partial code word, and
• each time the information quantity of the partial code word is iteratively increased, generating a dependent correlation value by correlating the partial code word having increased information quantity with a corresponding partial stored code word, the iterative increasing of the information quantity of the partial code word continuing until the whole code word is recovered by said step of recovering, and correlated with the whole stored code word by said step of generating, or the predetermined threshold exceeded.

An encoding data processing apparatus comprising:

• a hardware recovery processor operable to recover a partial code word that is composed of at least one part of a whole code word, each part including different data from the code word, the partial code word recovered from a corresponding unit of a watermarked material item such as an image or data stream, the marked material item composed of a plurality of units, the marked version formed by combining each part of the code word with one of the plurality of units,
• a correlator operable to generate for the watermarked material item a dependent correlation value by correlating the partial code word with a corresponding partial stored code word that is a part of a whole stored code word, and
• a detector operable to determine whether the whole stored code word is present in the watermarked material item based on the dependent correlation value for the partial code word exceeding a predetermined threshold, wherein
• when the dependent correlation value does not exceed the predetermined threshold, the correlator is operable to iteratively increase a number of parts of the partial code word used, to increase information quantity of the recovered partial code word,
• each time the information quantity of the partial code word is increased, the correlator is operable to generate a dependent correlation value by correlating the partial code word that having increased information quantity with a corresponding partial stored code word, the iterative increasing of the information quantity of the partial code word continuing until the whole code word is recovered by the recovery processor, and correlated with the whole stored code word by the correlator, or the predetermined threshold exceeded.

A system for identifying versions of a material item, the system comprising:

• an encoding data processing apparatus operable to form marked versions of the material item by combining each version with a code word having a plurality of parts, each part including different data from the code word, the material item composed of a plurality of units, each of the plurality of parts of the code word being combined with one of the plurality of units, and
• a detecting data processing apparatus operable to identify the code word present in a marked version of the material item, the detecting data processing apparatus comprising
• a hardware recovery processor operable to recover a partial code word composed of at least one of the plurality of parts of a code word from at least one of the plurality of corresponding units of the marked material item,
• a correlator operable to generate for the marked material item a dependent correlation value by correlating the partial code word with a corresponding partial stored code word that is a part of a whole stored code word, and
• a detector operable to determine whether the whole code word is present in the marked material item based on the dependent correlation value for the partial code word exceeding a predetermined threshold, wherein
• when the dependent correlation value does not exceed the predetermined threshold, the correlator is operable to iteratively increase a number of parts of the partial code word used, to increase information quantity of the recovered partial code word,
• each time the information quantity of the partial code word is increased, the correlator is operable to generate a dependent correlation value by correlating the partial code word having increased information quantity with a corresponding partial stored code word, the iterative increasing of the information quantity of the partial code word continuing until the whole code word is recovered by the recovery processor, and correlated with the whole stored code word by the correlator, or the predetermined threshold exceeded.